//
// execution/set_error.hpp
// ~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2022 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//

#ifndef ASIO_EXECUTION_SET_ERROR_HPP
#define ASIO_EXECUTION_SET_ERROR_HPP

#if defined(_MSC_VER) && (_MSC_VER >= 1200)
# pragma once
#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)

#include "asio/detail/config.hpp"
#include "asio/detail/type_traits.hpp"
#include "asio/traits/set_error_member.hpp"
#include "asio/traits/set_error_free.hpp"

#include "asio/detail/push_options.hpp"

#if defined(GENERATING_DOCUMENTATION)

namespace asio {
namespace execution {

/// A customisation point that delivers an error notification to a receiver.
/**
 * The name <tt>execution::set_error</tt> denotes a customisation point object.
 * The expression <tt>execution::set_error(R, E)</tt> for some subexpressions
 * <tt>R</tt> and <tt>E</tt> are expression-equivalent to:
 *
 * @li <tt>R.set_error(E)</tt>, if that expression is valid. If the function
 *   selected does not send the error <tt>E</tt> to the receiver <tt>R</tt>'s
 *   error channel, the program is ill-formed with no diagnostic required.
 *
 * @li Otherwise, <tt>set_error(R, E)</tt>, if that expression is valid, with
 *   overload resolution performed in a context that includes the declaration
 *   <tt>void set_error();</tt> and that does not include a declaration of
 *   <tt>execution::set_error</tt>. If the function selected by overload
 *   resolution does not send the error <tt>E</tt> to the receiver <tt>R</tt>'s
 *   error channel, the program is ill-formed with no diagnostic required.
 *
 * @li Otherwise, <tt>execution::set_error(R, E)</tt> is ill-formed.
 */
inline constexpr unspecified set_error = unspecified;

/// A type trait that determines whether a @c set_error expression is
/// well-formed.
/**
 * Class template @c can_set_error is a trait that is derived from
 * @c true_type if the expression <tt>execution::set_error(std::declval<R>(),
 * std::declval<E>())</tt> is well formed; otherwise @c false_type.
 */
template <typename R, typename E>
struct can_set_error :
  integral_constant<bool, automatically_determined>
{
};

} // namespace execution
} // namespace asio

#else // defined(GENERATING_DOCUMENTATION)

namespace asio_execution_set_error_fn {

    using asio::decay;
    using asio::declval;
    using asio::enable_if;
    using asio::traits::set_error_free;
    using asio::traits::set_error_member;

    void set_error();

    enum overload_type {
        call_member,
        call_free,
        ill_formed
    };

    template<typename R, typename E, typename = void, typename = void>
    struct call_traits {
        ASIO_STATIC_CONSTEXPR(overload_type, overload = ill_formed
        );

        ASIO_STATIC_CONSTEXPR(bool, is_noexcept = false);

        typedef void result_type;
    };

    template<typename R, typename E>
    struct call_traits<R, void(E),
            typename enable_if<
                    set_error_member<R, E>::is_valid
            >::type> :
            set_error_member<R, E> {
        ASIO_STATIC_CONSTEXPR(overload_type, overload = call_member);
    };

    template<typename R, typename E>
    struct call_traits<R, void(E),
            typename enable_if<
                    !set_error_member<R, E>::is_valid
            >::type,
            typename enable_if<
                    set_error_free<R, E>::is_valid
            >::type> :
            set_error_free<R, E> {
        ASIO_STATIC_CONSTEXPR(overload_type, overload = call_free);
    };

    struct impl {
#if defined(ASIO_HAS_MOVE)
        template <typename R, typename E>
        ASIO_CONSTEXPR typename enable_if<
          call_traits<R, void(E)>::overload == call_member,
          typename call_traits<R, void(E)>::result_type
        >::type
        operator()(R&& r, E&& e) const
          ASIO_NOEXCEPT_IF((
            call_traits<R, void(E)>::is_noexcept))
        {
          return ASIO_MOVE_CAST(R)(r).set_error(ASIO_MOVE_CAST(E)(e));
        }

        template <typename R, typename E>
        ASIO_CONSTEXPR typename enable_if<
          call_traits<R, void(E)>::overload == call_free,
          typename call_traits<R, void(E)>::result_type
        >::type
        operator()(R&& r, E&& e) const
          ASIO_NOEXCEPT_IF((
            call_traits<R, void(E)>::is_noexcept))
        {
          return set_error(ASIO_MOVE_CAST(R)(r), ASIO_MOVE_CAST(E)(e));
        }
#else // defined(ASIO_HAS_MOVE)
        template<typename R, typename E>
        ASIO_CONSTEXPR typename enable_if<
                call_traits<R &, void(const E &)>::overload == call_member,
                typename call_traits<R &, void(const E &)>::result_type
        >::type

        operator()(R &r, const E &e) const

        ASIO_NOEXCEPT_IF((
                call_traits<R &, void(const E &)>::is_noexcept))
                {
                        return r.set_error(e);
                }

        template<typename R, typename E>
        ASIO_CONSTEXPR typename enable_if<
                call_traits<const R &, void(const E &)>::overload == call_member,
                typename call_traits<const R &, void(const E &)>::result_type
        >::type

        operator()(const R &r, const E &e) const

        ASIO_NOEXCEPT_IF((
                call_traits<const R &, void(const E &)>::is_noexcept))
                {
                        return r.set_error(e);
                }

        template<typename R, typename E>
        ASIO_CONSTEXPR typename enable_if<
                call_traits<R &, void(const E &)>::overload == call_free,
                typename call_traits<R &, void(const E &)>::result_type
        >::type

        operator()(R &r, const E &e) const

        ASIO_NOEXCEPT_IF((
                call_traits<R &, void(const E &)>::is_noexcept))
                {
                        return set_error(r, e);
                }

        template<typename R, typename E>
        ASIO_CONSTEXPR typename enable_if<
                call_traits<const R &, void(const E &)>::overload == call_free,
                typename call_traits<const R &, void(const E &)>::result_type
        >::type

        operator()(const R &r, const E &e) const

        ASIO_NOEXCEPT_IF((
                call_traits<const R &, void(const E &)>::is_noexcept))
                {
                        return set_error(r, e);
                }
#endif // defined(ASIO_HAS_MOVE)
    };

    template<typename T = impl>
    struct static_instance {
        static const T instance;
    };

    template<typename T>
    const T static_instance<T>::instance = {};

} // namespace asio_execution_set_error_fn
namespace asio {
    namespace execution {
        namespace {

            static ASIO_CONSTEXPR const asio_execution_set_error_fn::impl
            &
            set_error = asio_execution_set_error_fn::static_instance<>::instance;

        } // namespace

        template<typename R, typename E>
        struct can_set_error :
                integral_constant<bool,
                        asio_execution_set_error_fn::call_traits<R, void(E)>::overload !=
                        asio_execution_set_error_fn::ill_formed> {
        };

#if defined(ASIO_HAS_VARIABLE_TEMPLATES)

        template <typename R, typename E>
        constexpr bool can_set_error_v = can_set_error<R, E>::value;

#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)

        template<typename R, typename E>
        struct is_nothrow_set_error :
                integral_constant<bool,
                        asio_execution_set_error_fn::call_traits<R, void(E)>::is_noexcept> {
        };

#if defined(ASIO_HAS_VARIABLE_TEMPLATES)

        template <typename R, typename E>
        constexpr bool is_nothrow_set_error_v
          = is_nothrow_set_error<R, E>::value;

#endif // defined(ASIO_HAS_VARIABLE_TEMPLATES)

    } // namespace execution
} // namespace asio

#endif // defined(GENERATING_DOCUMENTATION)

#include "asio/detail/pop_options.hpp"

#endif // ASIO_EXECUTION_SET_ERROR_HPP
